1. Field of the Invention
This invention relates generally to-fine needle aspiration biopsy apparatus and methods, and more particularly to a syringe for use in such procedures.
2. Description of the Prior Art
There is a U.S. Pat. No. 4,549,554 issued Oct. 29, 1985 to Markham which discloses a syringe with a detachable valve 28 located at its end to regulate vacuum, and an opening 46 in the syringe body to vent the device after use. One embodiment shown in FIG. 4 of the patent shows a stop pin 114 inserted in a hole 112 in the piston to hold the withdrawn piston, to hold the vacuum until the specimen has been secured.
A U.S. Pat. No. 4,967,762 issued Nov. 6, 1990 to DeVries discloses a fine needle aspiration biopsy syringe which, although it does not have a valve for control of vacuum, shows an O-ring on the needle mounting attachment and which normally covers an opening 72 in the attachment (FIG. 2). When the sample has been drawn, the ring is rolled away from the opening to vent the vacuum, whereupon the needle can be withdrawn without disturbing the specimen.
U.S. Pat. No. 4,986,278 issued Jan. 22, 1991 to Ravid et al. discloses a two piston design for a biopsy syringe device, and which has a valve located near its end to regulate a vacuum. The vacuum is used to regulate the position of a needle.
U.S. Pat. No. 4,619,272 issued Oct. 28, 1986 to Zambelli discloses an instrument for performing biopsies and which includes a valve 24 which can be turned to open it and admit air into the suction chamber 10.
While the Markham and DeVries devices have some desirable functional features as mentioned above, greater simplicity and convenience of use is needed. The reason is the fact that, in fine needle aspiration biopsy procedures, it is desirable to be able to place and direct the needle with precision and to operate the vacuum control and vent easily. The necessity of using two hands or inconvenient or unnatural finger movements in order to secure a sample, can make a device inconvenient, awkward or difficult to use. It is an object of the present invention to provide a fine needle aspiration biopsy device that is easier to use.